**5. Final remarks**

White wine protein instability has still been an important problem in the wine industry by the frequency of haze formation on the white and rose bottled wine. The grape variety and its grape sanitary conditions, 'terroir', the climate conditions during the grape maturation, the mechanical harvest and some winemaking operations could influence significantly the levels of unstable proteins in the wines. The principal proteins responsible for the protein haze are chitinases and thaumatin-like proteins, considered pathogenesis-related proteins (PR) with different thermostability and sizes. Many factors could affect their wine stability, such as wine exposition to high temperatures, wine pH variation, organic acids levels, metals composition, sulphur dioxide levels and the presence of phenolic composition and its degree of polymerisation. Some factors are yet unknown (X factors) but they influence protein precipitation. Even after many works that have been done in the last years, sodium bentonite has still been the most effective treatment to eliminate unstable proteins from white and rose wines. In fact, many products and treatments had been tested to remove these unstable proteins, such as proteases, different polysaccharides (chitin, chitosan, CMC, carrageenan), yeast mannoproteins, some of them show an interesting efficiency, such as carrageenan in a recent work. Finally, white wine proteins stabilisation has still been a problem for the wine industry, and it is necessary to continue developing new approaches to remove or mitigate this important problem. It is necessary to get new solutions to decrease the amount of bentonite used in the wine industry per year by those negative sensory impacts after wine treatment and by environmental concerns.
